Radiation sensitive ends down detecting apparatus and method

ABSTRACT

An apparatus and method for detecting ends of yarn on a textile yarn forming machine such as a spinning machine wherein radiation source and radiation detector mounted on and movable with a traveling unit direct radiation toward ends of yarn and respond to radiation reflected therefrom, the impingement of radiation onto the detector being amplified at a low signal to noise ratio through concentration of reflected radiation by a static reflector.

United States Patent 1 [111 3,803,822 Mulligan Apr. 16, 1974 [54]RADIATION SENSITIVE ENDS DOWN 3,523,413 8/1970 Ford et al. 57/81DETECTING APPARATUS AND METHOD 3,523,414 8/1970 Black et al 250/219 S XInventor: William L. Mulligan, Charlotte,

Parks-Cramer Company, Fitchburg, Mass.

Filed: Dec. 14, 1970 Appl. No.: 97,521

Assignee:

US. Cl. 57/34 R, 250/219 S Int. Cl D0lh 13/16 Field of Search 356/199,200, 238;

References Cited UNITED STATES PATENTS 7/l968 King 250/219 S PrimaryExaminer-Ronald L. Wibert Assistant Examiner-Orville B. Chew Attorney,Agent, or Firm-Parrott, Bell, Seltzer, Park & Gibson [5 7] ABSTRACT Anapparatus and method for detecting ends of yarn on a textile yarnfonning machine such as a spinning machine wherein radiation source andradiation detector mounted on and movable with a traveling unit directradiation toward ends of yarn and respond to radiation reflectedtherefrom, the impingement of radiation onto the detector beingamplified at a low signal to noise ratio through concentration ofreflected radiation by a static reflector.

1 Claim, 2 Drawing Figures mimmm 16 m4 $803322 a lllillllllllllllllllll1mm llllllllllllllllllllllllllllIll {8 INVENTOR: WI LUAM L. MULUGAN mwwATTORNEYS 1 RADIATION SENSITIVE ENDS DOWN DETECTING APPARATUS AND METHODThis invention is related to inventions owned in common with the presentinvention and disclosed in patents and applications entitled Apparatusand Method for Detecting, Piecing-Up and Reporting Ends Down on SpinningMachines, U.S. Pat. No. 3,486,319 issued Dec. 30, 1969; Apparatus andMethod For Detecting and Reporting Ends Down on Textile Machines, U.S.Pat. No. 3,523,413 issued Aug. 1 l, 1970; and Electric Circuit Means ForTextile Strand Ends Down Detecting Apparatus, filed Oct. 1, 1970 underSer. No. 77,101, now U.S. Pat. No. 3,659,409 issued May 2, 1972.

It has previously been proposed that the efficiency of textile machineoperators, and particularly of spinners working in the spinning room ofa textile mill, may be improved by providing apparatus including adetector mounted on or traveling with a traveling unit such as apneumatic cleaner, for patrolling textile yarn forming machines as thetraveling unit traverses the same and for providing an indication ofthose textile machines or sides of machines in need of correction ofimproper conditions, that is in needof the puttingup of ends down. Suchapparatus and components of circuitry therefor are the subject matter ofthe aforementioned related patents and application.

Operating apparatus in accordance with the teachings of theaforementioned related patents and application have been constructed inwhich radiation in the form of visible light from a source such as anincandescent lamp is directed toward ends of yarn on a textile yarnforming machine andvisible light reflected from the ends of yarn isdetected by a photomultiplier tube of conventional construction. Whilesuch operating embodiments are successful in determining the absence andpresence of yarns formed on atraversed machine,

certain difficulties have been encountered in maintainingan accuratedetermination .of the presence and absence of ends of yarn under certainadverse conditions.

More particularly, the amount of visible light reflected from the endsof yarn is relatively small and substantial amplif cation is required toraise any related electrical signal to .the level needed fordistinguishing between the presence and absence of ends of yarn at theyarn forming locations. In prior operating embodiments, suchamplification has been successfully accomplished through the use of'photoemissive devices, and particularly photomultipliers as mentionedabove. Photomultipliers are known to have tremendous amplificationcapability, and rely upon secondary electron emission in responding tolow light levels. One substantial disadvantage of the photomultiplier isthat thermionic emission originating within the photomultiplier isamplified together with any light initiated signal and appears as asignificant noise component in the resultant total signal where highsensitivity is sought. The presence of such noise is often furthercomplicated by the relatively high ambient levels of visible lighttypically found in a textile mill room where the'apparatus is operating.High ambient illumination levels and high signal to noise ratios have,in particularly severe circumstances, combined with other factors in theoverall apparatus arrangement to bring about unacceptable inac- 2curacies in determination of the presence and absence of yarn.

In view of the above, it is an object of the present invention to avoidthe introduction of noise into a signal indicative of radiationreflected from an end of yarn from ends of yarn eliminates thepossibility of noise introduction by thermionic emission or similareffects as is common with any active amplification means such as thephotomultipliers used in prior related developments.

Some of the objects and advantages of the invention having been stated,others will appear as the description proceeds, when taken in connectionwith the accompanying drawings, in which:

FIG. I is an end elevation view, in partial section, of an apparatus inaccordance with the present invention shown during traversal of atextile yarn forming machine; and

FIG. 2 is an enlarged elevation, in section, through a detector headforming a portion of the apparatus of FIG. 1, illustrating moreparticularly the arrangement of radiation source and radiation detectorin accordance with the present invention.

Referring to the drawings, the apparatus of the present invention isthere disclosed in operating relation to a textile yarn forming machine,namely a ring spinning frame 10. While only a single spinning frame 10is illustrated, it is to be understood that the frame 10 may be of oneof a substantial number of spinning machines arranged in rows in aspinning room, in patterns which are substantially conventional. Atraveling unit, here illustrated as a pneumatic cleaner 20, is supportedabove the textile machine 10 for traversing the same along apredetermined path of travel. The specific apparatus chosen forillustration in the drawings is substantially identical to the fourthembodiment of the traveling pneumatic cleaner disclosed in U.S. Pat. No.3,304,571 issued on Feb. 21, 1967 and owned in common with the presentinvention, but it must be understood at the outset that a wide varietyof other patrolling devices are contemplated as useful in thecombination of this invention and that the invention is accordingly notto be limited solely to traveling cleaners.

The traveling cleaner 20 is supported for movement along a track 21extending above the spinning frame 10 and includes blowing and suckingair sleeves 22 and 23 depending on either side of the spinning frame 10from a main fan housing, for removing lint and the like from thespinning frame 10 and the floor by currents of air.

As is disclosed more fully in the aforementioned patent directed to thecleaner structure, drive means and a fan are provided for inducing theflow of currents of air for such cleaning. While the traveling cleaner20 may be arranged to traverse a plurality of textile machines such asthe spinning frame 10, the present invention contemplates also that thetraveling cleaner 20 or the manner in which the cleaner is supported andarranged for traversing a textile machine may be changed in varyingways, including limiting the path of travel of the cleaner to traversalof a single machine only.

Conventional ring spinning frames in wide use in the textile industry ofthe world at the present time include a creel portion wherein aplurality of bobbins of roving R are suspended, drafting systems D towhich the roving is supplied, and spindles equipped with bobbins B onwhich spun yarn is wound. In spinning the yarn Y in conventional mannerand packaging the yarn onto bobbins B mounted on the spindles of thespinning machine 10, roving passes through the drafting systems D totravelers mounted on spinning rings 11 encircling each of the pluralityof spindles driven in rotation from the center shaft or tape drum of themachine. In passing between the drafting systems and the travelers, theyarn Y is exposed to detection by means mounted within a detector head30 as will now be described.

The detector head 30 depends from the traveling cleaner 20, between theblowing and sucking air sleeves thereof, and includes a casing 31 whichencloses a radiation detector generally indicated at 32 and a radiationsource generally indicated at 34. As proposed in the aforementionedrelated patents and application, the traveling cleaner mounts two ofsuch detector heads 30, for monitoring both sides of the spinning frame10 during traversal thereof by the traveling cleaner 20. For purposes ofthe present disclosure, discussion will be directed particularly to onedetector head 30, with it being understood that both of the detectorheads 30, 30 are identical in structure and operation.

The radiation detector 32 will be noted as including a detector casing36 having a sensing element 39 disposed therewithin. Desirably, thesensing element 39 is a photoconductive element such as a sulfideresistor conducting a flow of electrical current which is dependent uponimpingement of radiation. Through provision of the element 39, theradiation detector 32 is rendered responsive by electrical variation toradiation such as is reflected from the ends of yarn Y normally beingformed at locations along the spinning frame 10.

in accordance with the present invention, static, reflective radiationconcentrating means is mounted in predetermined relation to the sensingelement 39 for amplifying at a low signal to noise ratio the impingementthereonto of radiation reflected from ends of yarn Y. Desirably, theconcentrating means is defined by a parabolic internal surface of thedetector casing 36 reflective as to radiation emitted by the radiationsource 34, with the sensing element 39 having its active portion lyingat the focus of the parabolic surface (FIG. 2). As will be understood,the internal surface of the casing 36 concentrates onto the sensingelement 39 radiation which reaches the detector 32 from within apredetermined, generally right circular cylindrical, field of view(illustrated by phantom lines in the drawing).

For purposes of minimizing the maintenance required by the radiationdetector 32, and for other reasons which will be brought out more fullyhereinafter, it is preferred that the radiation to which the detector 32responds be radiation in the range of wavelengths known as infrared andthat the sensing element 39 be a lead sulfide resistor. Where infraredradiation is employed, the reflective surface of the detector casing 32which functions as the static, reflective radiation concentrating meansand which amplifies the impingement of radiation onto the sensingelement 39 may be a polished metal surface which need not be silvered orotherwise specially treated. Polished metal surfaces havingcharacteristics of reflectivity for infrared radiation more readilymaintain a high reflectivity under textile mill operating conditionsthan do those surfaces which are highly reflective at wavelengthsvisible to the human eye. As is known, the concentrating and amplifyingeffects of a parabolically curved surface may be employed forsubstantially all wavelengths of radiation, including light visible tothe human eye, but the difficulty of maintaining a highly reflectivesurface for visible light renders the choice of visible light as theradiation used less than wholly desirable where a static, radiationconcentrating means as contemplated by this invention is used.

Radiation reaching the detector 32 from ends of yarn Y, forconcentration onto the sensing element 39, originates from a radiationsource 34 including a source casing 38 within which is mounted asuitable means for emitting radiation, such as a suitable incandescentlamp 40. Desirably, the housing 38 includes a generally parabolicinterior surface wall reflective for radiation of the type to which thedetector 32 responds, and the filament of the incandescent lamp 40 ispositioned generally at the focal point of the parabolic surface. Whereinfrared radiation is employed, the incandescent lamp 40 is selected tobe a type emitting radiation rich in infrared wavelengths and ascreening filter 41 is positioned to ensure that radiation directedoutwardly of the source 34 is of a desirable wavelength characteristic.Tuning of the detector 32 and source 34 to a common band of infraredradiation is accomplished by the provision of a corresponding filter 42in the radiation detector 32.

It is to be noted that the infrared radiation source 34 and infraredradiation detector 32 are mounted within the detector head 30 so thatthe generally right circular cylindrical fields thereof intersect in anelongate zone spaced forwardly of the detector head 30 (dotted lines inFIGS. 1 and 2). As will be understood, the tunnel" field of viewavailable to the infrared radiation detector 32, being substantiallyright circular cylindrical throughout its extent, ensures properresponse of the infrared radiation detector to infrared radiationemitted from the source 34 and reflected from an end of yarn Y at anypoint within the intersecting zone of the fields of the source 34 anddetector 32 even should that zone be displaced toward or away from thespinning frame 10. By this means, incorrect responses otherwise possiblyintroduced by sway or deflection of the detector head 30 due to movementof the traveling cleaner 20 are minimized.

The adoption of the infrared band of wavelengths as the radiation towhich the source 34 and detector 32 are tuned provides other and furtherbenefits, in the combination of this invention, in that infrareddetectors having the characteristics described above are more ruggedthan photomultipliers and thus more easily withstand any rough usageoccurring in a textile mill application. Further, such infrareddetectors operate at lower voltage levels than photomultipliers and areavailable at lower cost, thereby opening possibilities for moreeconomical construction and maintenance for the combination of thepresent invention. Finally, the ambient level of infrared radiation in atextile mill room is quite low, as compared to visible light, so as tofacilitate reliance on the static, radiation concentrating means of thisinvention in obtaining the needed amplification of radiation reflectedfrom ends of yarn.

What is claimed is:

1. In an apparatus for monitoring ends of yarn normally being formed atlocations along a textile yarn forming machine and including a travelingunit movable relative to the yarn forming locations, a radiation sourcemounted on the traveling unit and moving therewith for directingradiation toward ends of yarn being formed at the yarn forminglocations, a radiation detector mounted on the traveling unit and movingtherewith and having a sensing element for responding by an electricalvariation to radiation impinging thereon, and electronic circuitryoperatively connected with the detector for distinguishing betweenelectrical variations of said sensing element indicative of the presenceand absence of ends of yarn at the yarn forming locations, thatimprovement which comprises first casing means enclosing said radiationsource and defining a parabolic surface for reflecting radiation emittedtherefrom into a collimated beam, filter means on said first casingmeans for tuning radiation projected therefrom to a predetermined rangeof infrared radiation wavelengths; second casing means enclosing saidsensing element and defining a parabolic surface lying in predeterminedrelation to said sensing element for concentrating the impingement ontosaid sensing element of radiation reflected from ends of yarn beingformed at the yarn forming locations, said parabolic surfaceconcentrating onto said sensing element radiation projected from saidfirst casing means and reflected to said sensing element from within apredetermined field of view, and filter means on said second casingmeans for limiting radiation reaching said parabolic surface thereof tosaid predetermined range of wavelengths.

1. In an apparatus for monitoring ends of yarn normally being formed atlocations along a textile yarn forming machine and including a travelingunit movable relative to the yarn forming locations, a radiation sourcemounted on the traveling unit and moving therewith for directingradiation toward ends of yarn being formed at the yarn forminglocations, a radiation detector mounted on the traveling unit and movingtherewith and having a sensing element for responding by an electricalvariation to radiation impinging thereon, and electronic circuitryoperatively connected with the detector for distinguishing betweenelectrical variations of said sensing element indicative of the presenceand absence of ends of yarn at the yarn forming locations, thatimprovement which comprises first casing means enclosing said radiationsource and defining a parabolic surface for reflectiNg radiation emittedtherefrom into a collimated beam, filter means on said first casingmeans for tuning radiation projected therefrom to a predetermined rangeof infrared radiation wavelengths; second casing means enclosing saidsensing element and defining a parabolic surface lying in predeterminedrelation to said sensing element for concentrating the impingement ontosaid sensing element of radiation reflected from ends of yarn beingformed at the yarn forming locations, said parabolic surfaceconcentrating onto said sensing element radiation projected from saidfirst casing means and reflected to said sensing element from within apredetermined field of view, and filter means on said second casingmeans for limiting radiation reaching said parabolic surface thereof tosaid predetermined range of wavelengths.